The present invention generally relates to high data rate wireless communication networks, and particularly relates to mobility management in data-only networks, such as in TIA/EIA/IS-856 based networks.
Advanced high data rate wireless communication networks offer subscribers the range of applications and convenience available only with relatively high bandwidth communication between the subscribers' access terminals and the wireless access network. One approach to achieving higher bandwidth involves the use of data-only access networks, with first generation evolution, data-only (1xEVDO) networks representing an example of this approach.
1xEVDO networks generally follow the TIA/EIA/IS-856 interim standard, which specifies a framework for high data rate (HDR) packet data communication between a public data network (PDN), such as the Internet, and subscribers' access terminals. 1xEVDO networks forego the use of a mobile switching center (MSC), instead of using a packet control function (PCF) to route subscriber data between a packet data serving node (PDSN) interfaced to a PDN and an access network controller (ANC) supporting the subscribers' access terminals.
Each ANC manages the radio resources for one or more access network transceiver systems (ANTS), which provide the actual radio resources for radio frequency control and data signaling between the wireless access terminals and the network. Typically, the ANCs are arranged in subnets, with one or more ANCs per subnet. The PCF supports access terminal connections across multiple subnets and is responsible for routing data to the appropriate ANC within an access terminal's current subnet.
Mobility management, that is, tracking movement of access terminals between ANCs and between subnets, is complicated by the nature of packet data communications. Many types of packet data sessions, such as web browsing, involve intermittent activity with relatively long periods of dormancy. For example, an access terminal may establish a connection to the network through a given ANC within a given subnet and then, while dormant, move to the service area of another ANC, either in the same subnet, or possibly within a different subnet.
This type of dormant handoff poses challenges in managing the mobility of an access terminal that has an open connection with the network but moves between ANCs and subnets within the network during periods of dormancy. Ideally, an approach to mobility management within the network would minimize network control traffic overhead, require only minimal changes at the PCF and ANC to maintain compatibility with current implementations of those entities, and provide flexibility in defining the size of subnets within the network.